• Prof. Thaddeus B. Massalski - Carnegie Mellon University, USA (Professor will be the prize-winner of The Czochralski Award of the year 2006 for the achivements in Materials Science.)

"Alloy Phase Diagrams: Opportunities, Problems and Applications "

In the context of materials, there is probably no other broad subject that impinges more on the various aspects of materials science and technology than the description of phase stability in terms of temperature and composition, known as a Phase Diagram. Phase diagrams are the "road maps" that guide and direct us to our numerous goals in fabrications, developments, heat treatment, properties and basic science. In this presentation, I shall discuss briefly the three laws of thermodynamics, including considerations of how phase diagrams are determined and assessed, and how they can be judged in terms of thermodynamic parameters. I shall then turn attention to metastability and concepts that arise when, because of kinetics, ideal equilibrium conditions can be suppressed or altered by heat treatment, such as cooling, rapid quenching, annealing etc. The use of phase diagrams and opportunity which they present for development of unusual properties, or structures, or features will be considered next, and will be followed by expectation of phase behavior, and phase diagram features, at temperatures between 0C and 0K, where the third law becomes increasingly important and kinetics are reduced. Finally, the process of assessing phase diagrams through the examination of published work on experimental determinations, on modeling calculations, and on measured thermodynamic quantities will be considered. Here, I will stress the usefulness of international cooperation in this whole area.

  • Prof. Wolf-Dieter Schneider - Ecole Polytechnique Fédérale de Lausanne (EPFL), Institut de Physique des Nanostructures, Lausanne, Switzerland

"Fabrication of ordered atomic-scale structures - a step towards future atomic-scale technology"

The quest of a reliable method for fabricating ordered atomic-scale structures is a prequisite for future atomic-scale technology. The interest in such nanostructured materials, consisting of building blocks of a small number of atoms or molecules, arises from their promising new optic, catalytic, magnetic and electronic poperties, which are fundamentally different from their macroscopic bulk counterparts: small is different. Here we present three examples concerning atomic and supramolecular self-assembly investigated by low-temperature scanning tunneling microscopy (STM). (i) The self-assembly of a two-dimensional array of individual Ce adatoms (the "ultimate" building block) on a metal surface based on long-range interactions between adatoms mediated by surface state electrons [1,2]. Ce is a magnetic atom, and such a hexagonal superlattice of magnetic adatoms might be useful for the development of future atomic-scale magnetic devices. (ii) The conservation of chirality in a hierarchical supramolecular self-assembly of pentagonal symmetry of the organic molecule rubrene on a reconstructed Au(111) surface [3]. We show the spontaneous chiral resolution of the racemate into disjoint homochiral complex architectures and demonstrate the ability to monitor directly the evolution of chiral recognition processes on the molecular and supramolecular level. (iii) Using the highly localized current of electrons tunneling through a double barrier STM junction, we excite luminescence from a selected C 60 molecule in the surface layer of fullerene nanocrystals self-assembled on an ultrathin NaCl film on Au(111). In the observed fluorescence and phosphorescence spectra, pure electronic as well as vibronically induced transitions of an individual C 60 molecule are identified, leading to unambiguous chemical recognition on the single-molecular scale [4].

[1] F. Silly, M. Pivetta, M. Ternes, F. Patthey, J. P. Pelz, and W.-D. Schneider, Phys. Rev. Lett. 92, 016101 (2004).
[2] M. Ternes, C. Weber, M. Pivetta, F. Patthey, J. P. Pelz, T. Giamarchi, F. Mila, and W.-D. Schneider,
Phys. Rev. Lett. 93, 146805 (2004).
[3] M.-C. Blüm, E. Cavar, M. Pivetta, F. Patthey, W.-D. Schneider, Angew. Chem. Int. Ed. 44 , 5334 (2005).
[4] E. Cavar, M.-C. Blüm, M. Pivetta, F. Patthey, M. Chergui, and W.-D. Schneider, Phys. Rev. Lett. 95, 196102 (2005).

  • Prof. Yuly V. Milman - Department of Physics of High-Strength and Metastable Alloys, Frantsevich Institute for Problems of Materials Science, Ukrainian Academy of Sciences, Kiev, Ukraine

"Peculiarities of mechanical behavior of nanocrystalline and noncrystalline materials."

The review of the mechanical behavior of nanocrystalline (NQ) and noncrystalline (amorphous (MG) and quasicrystalline (QC)) materials is given. Peculiarities of deformation mechanism for NQ materials are connected with the practically absence of dislocations in the body of grain (dislocations go out into the grain boundaries due to image forces) and realization of deformation in the grain boundaries.
In MG the dislocation mechanism of deformation is discussed for the range of nonhomogenious deformation. Strain hardening and localization of deformation in MG is considered. s s of MG consist of thermal and very big athermal components. Thermal component is close to the thermal component of crystalline state. s s and hardness H of MG are very high, but NQ can have higher values of s s and H if d < 100 nm.
Plastic deformation of quasicrystals is of dislocation type, but Burgers vector of dislocations contains phason component, and dislocation movement is accompanied by the gradual destroying of quasicrystalline structure and in some cases by phase transition to crystalline state. The hardness of quasicrystals increases after annealing and decreases during deformation. QC with the nanosize grains (NQC) is the especial class of materials, because energy of dislocation connected with phason defects is proportional to d (not lnd as elastic energy of dislocations in crystals).For this reason plasticity of NQC is more than in QC. Composite materials on the base of NQ, MG and QC can have high level of mechanical properties.

  • Zbigniew Klos , Jerzy Grygorczuk - Space Research Centre of Polish Academy of Sciences, Bartycka 18a, Warszawa 01-716, Poland

"Space Programs: a challenge for material engineering"

Space Programs are, by their nature, interdisciplinary and prefer holistic approach. Reliability and redundancy are governing principles in preparing space missions. The space sector is generally more oriented toward using and combining existing technologies than toward generating new ones. Although, this "spin-in" approach dominates in the policy of primary space contractors, it still leaves room for new innovative elements and solutions provided by subcontracting enterprises, usually belonging to the state-of-art unit in material engineering. The good example of that is the parallel activity of the European Space Technology Master Plan (ESTMP) - outlook for future and solutions for space instrumentation implemented now in the planetary probes. The technology of material coating, tribology and advanced miniaturization are key areas that respond to continuously increasing requirements for new sensors, power sources and propulsion systems with very low mass, volume and power consumption. The main challenge of space engineering follows from unusual environmental requirements and constraints (heavy loads and vibration during launch, microgravity, vacuum, thermal gradients, increased doses of radiation) that forces space specific solutions. The Space Research Centre PAS has been involved in design, development, tests and analyses of the advanced instruments prepared for European landers on Titan (Cassini /Huygens) and cometary nucleus (Rosetta). In particular, an original cometary nucleus penetrator onboard Philae(Rosetta lander), working at unusual conditions in space, was a challenge for mechanical design and material engineering. The device contains novel solutions and was developed within close international cooperation.